[Intel-gfx] [PATCH 2/3] drm/i915: Remove PSR Perf Counter for SKL+

[Jindal, Sonika]

Hi Rodrigo,

Which platform have you observed this issue on?
This looks really strange.
Have you checked whether we are able to enter PSR at sink side or not in such cases?
Are we sure we are not entering PSR? I mean the PSR_STATE register says it correctly?

Regards,
Sonika

-----Original Message-----
From: Intel-gfx [mailto:intel-gfx-bounces at lists.freedesktop.org] On Behalf Of R, Durgadoss
Sent: Thursday, November 19, 2015 11:39 AM
To: Vivi, Rodrigo; intel-gfx at lists.freedesktop.org
Cc: Vivi, Rodrigo
Subject: Re: [Intel-gfx] [PATCH 2/3] drm/i915: Remove PSR Perf Counter for SKL+



>-----Original Message-----
>From: Intel-gfx [mailto:intel-gfx-bounces at lists.freedesktop.org] On 
>Behalf Of Rodrigo Vivi
>Sent: Thursday, November 19, 2015 6:10 AM
>To: intel-gfx at lists.freedesktop.org
>Cc: Vivi, Rodrigo
>Subject: [Intel-gfx] [PATCH 2/3] drm/i915: Remove PSR Perf Counter for 
>SKL+
>
>Whenever DMC firmware put the HW into DC State a bunch of registers 
>including this perf counter is reset to 0 and never restored.
>
>So, even with PSR active and working we could still read
>"Performance_Counter: 0" what will misslead people to believe PSR is 
>broken.
>
>So, it is better to remove this counter information while we don't have 
>a better way to track PSR residency.

Agreed..

Reviewed-by: Durgadoss R <durgadoss.r at intel.com>

Thanks,
Durga

>
>Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
>---
> drivers/gpu/drm/i915/i915_debugfs.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/gpu/drm/i915/i915_debugfs.c 
>b/drivers/gpu/drm/i915/i915_debugfs.c
>index 038d5c6..71e1666 100644
>--- a/drivers/gpu/drm/i915/i915_debugfs.c
>+++ b/drivers/gpu/drm/i915/i915_debugfs.c
>@@ -2580,8 +2580,11 @@ static int i915_edp_psr_status(struct seq_file *m, void *data)
> 		}
> 	seq_puts(m, "\n");
>
>-	/* CHV PSR has no kind of performance counter */
>-	if (HAS_DDI(dev)) {
>+	/*
>+	 * VLV/CHV PSR has no kind of performance counter
>+	 * SKL+ Perf counter is reset to 0 everytime DC state is entered
>+	 */
>+	if (IS_HASWELL(dev) || IS_BROADWELL(dev)) {
> 		psrperf = I915_READ(EDP_PSR_PERF_CNT) &
> 			EDP_PSR_PERF_CNT_MASK;
>
>--
>2.4.3
>
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